108 IOWA ACADEMY OF SCIENCE 



pecially instructive exposures are now displayed. The valley 

 here is quite deep and narrow. There are, on one side of 

 the creek, the ruins of an old lime-kiln. The St. Louis lime- 

 stone, which was formerly quarried at this point to supply the 

 kiln, rises about twenty feet above the bed of the stream. Two 

 hundred feet to the southeast, in another bend of the creek, 

 the gypsum plate, overlain by thirty to forty feet of reddish, 

 sandy shale, outcrops at' water-level. Northwest of the lime-kiln, 

 about 400 feet, on the opposite side of the Soldier gorge, in the 

 clay pit of the brick plant, forty feet of coal measures are well 

 displayed. It seems hardly possible that the gypsum-plate, here 

 twenty-five feet in thickness, should wedge out abruptly and com- 

 pletely in so short a distance. 



The most illuminating section of all in the entire region is 

 that at the south end of the long narrow ridge which separates 

 Soldier valley from that of the Des Moines river. Two excep- 

 tionally fine artificial exposures supplement the natural out- 

 croppings of strata. On the one side of the ridge the excavation 

 for one of the abutments for the country highway viaduct over 

 the Soldier gorge discloses, in fresh, clean face, over seventy-five 

 feet of the pink shales which immediately overlie the 4 gypsum. 

 The latter lies in the bed of the creek a short distance away. The 

 Kohl Brewery section is near by, although now nearly com- 

 pletely obscured by talus. The two sections, which are easily 

 matched by the sandstone ledges, together give the following 

 sequence : 



SECTION AT LOWER VIADUCT OVER SOLDIER CREEK. 



Feet 



8. Till, gray and pebbly 10 



7. Shale, light reddish, sandy, banded 35 



6. Sandstone, soft, buff, calcareous, massive 5 



5. Shale, pink and white, sandy, in alternate layers.. 25 



4. Sandstone, massive, buff 2 



3. Shale, bluish 2 



2. Shale, brown, sandy, with gypsum layers 7 



1. Gypsum, massive (exposed) 10 



This exposure is the most extensive one of the pink shales 

 yet disclosed. The thickness of the latter is therefore at least 

 100 feet. 



On the opposite, or north side of the high ridge, is the huge 

 open clay-pit of the Fort Dodge Brick and Tile Company. The 



